Place them under three long boxes. Select the bottom polygons of the boxes and assign them a white self illuminated material like as I have done in the image below.

To get a more realistic illumination I have enabled Final Gather in indirect illumination. I have put a quite high number in samples to make the final render (600).

After you've made the room you must create the water. We can do that with a simple box. To create the small waves on the surface you have different possibilities (or with a material or by polygons). For a transparent water material create a Raytrace material (it must be transparent and a bit reflective). To create a wave effect put in the bump map a noise map with a quite small size; to simulate through geometry deformation the noise/wave effect you must apply to the box a noise modifier. The wave size will influence the caustic shapes. Big waves/noise = Big caustic shapes!
After you've made all the objects you must create a MR. Area Omni light on the top of the water in the center of the room as the image below shows.